Since the early days of the MetroCard, the Metropolitan Transportation Authority has given its riders a discount for buying in bulk, but that may be about to change.

MTA Chairman Joseph Lhota said Wednesday the authority will consider eliminating the 7% discount riders receive for buying pay-per-ride MetroCards when fares go up next March.

The discount is akin to a baker’s dozen — an extra bagel tossed into the bag, a reward to loyal customers at a marginal cost to the baker. Speaking to reporters Wednesday morning after a speaking engagement in Manhattan, Lhota recalled the discount as a longstanding tradition, with riders getting a free eleventh token in every pack of 10.

(In fact, an MTA spokesman later clarified, that discount was debated, but never actually put into place.)

When the MTA migrated to MetroCards, it cut riders a deal. Feed a $10 bill into a vending machine for a pay-per-ride card, and out comes a card with $10.70 loaded onto it, a bonus that the MTA says drives down the cost of a subway or bus ride from $2.25 to $2.10. (The percentage discount has fluctuated over time, reaching as high as 20%; the total cost to the MTA of giving that bonus was not immediately available.)

But now, with the MTA needing to raise $450 million by raising fares and tolls systemwide next year, Lhota questioned whether “the depth or size of the discount is necessary.”

In internal deliberations about the fare-raising process, he said, some have warned that taking away the 7% bonus would lead riders to stop buying MetroCards worth at least $10 in favor of individual rides.

“I don’t buy it at all,” Lhota said. “New Yorkers love convenience.”

Advocates for subway riders said the discount would hurt low-income riders, who cannot easily afford other options, like the $29 seven-day unlimited MetroCard.

Eliminating the discount is “no different than a fare hike,” the nonprofit Straphangers Campaign said in a response to Lhota’s comments.

Gene Russianoff, senior attorney at the Straphangers Campaign, said it was a mistake to view the discount as a tradition held over from previous years. It was a deliberate policy decision at the introduction of the MetroCard, in 1994, to provide an accessible option for riders who did not ride the subway regularly enough to benefit from an unlimited ride card, or could not afford one.

“I don’t think it’s a throwback or vestigial, I think it arguably was an attempt to help out the little guy,” Russianoff said. “That’s what the whole debate was about 15 years ago.”

The MTA will unveil its fare increase proposals in mid-October, Lhota said, and will hold public hearings in the second and third weeks of November. The MTA Board of Directors will vote in December on the fare increase, which is a key component of the authority’s $13.1 billion 2013 budget.

The MTA currently receives an average of $1.63 per rider because of the discounts to the $2.25 stated fare.